Generation of balanced pulse pairs based on a dual-chip coupling structure.

An asymmetric Mach-Zehnder interferometer (AMZI) is an essential device to generate pulse pairs in quantum key distribution systems. An AMZI based on a dual-chip coupling structure in a silica-on-silicon planar light wave circuit platform is proposed, which includes a variable optical splitter (VOS), a delay line (DL), and a directional coupler (DC). The AMZI chip is divided into a VOS-DL part and a DC part, and the two parts are independently manufactured and then coupled. Since the DC part occupies the smallest area of the AMZI chip and is most sensitive to manufacturing errors, separate production can reduce the process difficulty and fabrication errors. In the experiment, balanced pulse pairs with a delay time of 402 ps are obtained in the condition of single photon transmission, and the excess loss is 0.8 dB. This dual-chip coupling structure can improve the yield and reduce the manufacturing cost when producing large chips.

Mild and asymptomatic influenza B virus infection among unvaccinated pregnant persons: Implication for effectiveness of non-pharmaceutical intervention and vaccination to prevent influenza.

BACKGROUND: We estimated symptomatic and asymptomatic influenza infection frequency in community-dwelling unvaccinated pregnant persons to inform risk communication. METHODS: We collected residue sera from multiple antenatal-care blood draws during October 2016-April 2017. We determined influenza infection as seroconversion with ≥ 4-fold rise in antibody titers between any two serum samples by improved hemagglutinin-inhibition assay including ether-treated B antigens. The serology data were linked to the results of nuclei acid testing (rRT-PCR) based on acute respiratory illness (ARI) surveillance. RESULTS: Among all participants, 43 %(602/1384) demonstrated serology and/or rRT-PCR evidenced infection, and 44 %(265/602) of all infections were asymptomatic. ARI-associated rRT-PCR testing identified only 10 %(61/602) of total infections. Only 1 %(5/420) of the B Victoria cases reported ARI and had a rRT-PCR positive result, compared with 33 %(54/165) of the H3N2 cases. Among influenza ARI cases with multiple serum samples, 19 %(11/58) had seroconversion to a different subtype prior to the illness. CONCLUSIONS: The incidence of influenza B infection in unvaccinated pregnant persons is under-estimated substantially. Non-pharmaceutical intervention may have suboptimal effectiveness in preventing influenza B transmission due to the less clinical manifestation compared to influenza A. The findings support maternal influenza vaccination to protect pregnant persons and reduce consequent household transmission.

Incidence rates of influenza illness during pregnancy in Suzhou, China, 2015-2018.

BACKGROUND: Data on influenza incidence during pregnancy in China are limited. METHODS: From October 2015 to September 2018, we conducted active surveillance for acute respiratory illness (ARI) among women during pregnancy. Nurses conducted twice weekly phone and text message follow-up upon enrollment until delivery to identify new episodes of ARI. Nasal and throat swabs were collected ≤10 days from illness onset to detect influenza. RESULTS: In total, we enrolled 18 724 pregnant women median aged 28 years old, 37% in first trimester, 48% in second trimester, and 15% in third trimester, with seven self-reported influenza vaccination during pregnancy. In the 18-week epidemic period during October 2015 to September 2016, influenza incidence was 0.7/100 person-months (95% CI: 0.5-0.9). In the cumulative 29-week-long epidemic during October 2016 to September 2017, influenza incidence was 1.0/100 person-months (95% CI: 0.8-1.2). In the 11-week epidemic period during October 2017 to September 2018, influenza incidence was 2.1/100 person-months (95% CI: 1.9-2.4). Influenza incidence was similar by trimester. More than half of the total influenza illnesses had no elevated temperature and cough. Most influenza-associated ARIs were mild, and <5.1% required hospitalization. CONCLUSIONS: Influenza illness in all trimesters of pregnancy was common. These data may help inform decisions regarding the use of influenza vaccine to prevent influenza during pregnancy.

Incidence of acute diarrheal illness in Chinese communities: a meta-analysis.

BACKGROUND: Acute diarrheal illness (ADI) is an important public health problem worldwide. We estimated the morbidity, distribution, and burden of self-reported ADI in China over the last three decades. METHODS: We used the keywords "diarrhea and morbidity" to identify studies published in Chinese by searching CNKI, WANFANG, Chongqing VIP, and SinoMed. Studies published in English were identified using the keywords "diarrhea, morbidity, and China" to search Pubmed/Medline, Embase, and Cochrane Library Data. All articles published before Dec 31, 2014 were included in the search. Data were extracted and the pooled 2-week incidence rate of ADI was calculated using the fixed-effects or random-effects model according to statistical testing for homogeneity. The incidences of each subgroup (organized by age, location, study period) were also calculated. Publication bias was examined using Begg's test. Data manipulation and statistical analyses were undertaken using R-2.15.1 software. RESULTS: We estimated that the pooled 2-week prevalence of ADI in China was 2.04% (95% CI: 1.48-2.79) and that the corresponding incidence rate was 0.53 (95% CI: 0.38-0.73) episodes per person-year. The ADI rate was highest among children aged < 5 years (1.43 episodes per person-year), and it was slightly higher in males than in females (0.58 vs 0.52 episodes per person-year). From 1980 to 2012, there was a significant decrease in the incidence of ADI, from 0.82 to 0.48 episodes per person-year, but the ADI incidence was consistent over the last two decades. Additionally, the incidence of ADI was higher in rural areas and in west China and peaked in the summer months. CONCLUSIONS: The current study indicates that ADI caused a substantial disease burden in China in the last 30 years, especially in rural areas and west China, where sanitation conditions were relatively poor. These findings highlight the importance of further investigation of the specific causes of and effective preventive measures for ADI.

The fifth influenza A(H7N9) epidemic: A family cluster of infection in Suzhou city of China, 2016.

OBJECTIVE: Influenza A(H7N9) virus is known for its high pathogenicity in human. A family cluster of influenza A(H7N9) virus infection was identified in Suzhou, China. This study aimed to investigate the possibility of human-to-human transmission of the virus and examine the virologic features of this family cluster. METHODS: The clinical and epidemiologic data of two patients in the family cluster of influenza A(H7N9) virus infection were collected. Viral RNA in samples derived from the two patients, their close contacts, and the environments with likely influenza A(H7N9) virus transmission were tested by real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assay. Hemagglutination inhibition (HI) assay was used to detect virus-specific antibodies. Genetic sequencing and phylogenetic analysis were also performed. RESULTS: The index patient (Case 1), a 66-year old man, was virologically diagnosed with influenza A(H7N9) virus infection 12days after experiencing influenza-like symptoms, then died of multi-organ failure. His 39-year old daughter (Case 2), denying any other exposure to influenza A(H7N9) virus, became infected with influenza A(H7N9) virus following taking care of her father during his illness. Sequencing viral genomes isolated from the two patients showed nearly identical nucleotide sequence, and genetically resembled the viral genome isolated from a chicken in the wet market where the index patient once visited. All three influenza A(H7N9) viruses shared S138A, G186V, Q226L mutations in HA (H3) protein and a single basic amino acid (PEIPKGR↓G) at the cleavage site. CONCLUSIONS: Human-to-human transmission of influenza A(H7N9) virus most likely occurred in this household. The three-amino-acid mutations in HA protein were discovered in this study, which might have increased the binding affinity of influenza A(H7N9) virus to the receptor on trachea epithelial cells to facilitate viral transmission among humans.

Influenza A(H7N9) Virus Antibody Responses in Survivors 1 Year after Infection, China, 2017.

Avian influenza A(H7N9) virus has caused 5 epidemic waves in China since its emergence in 2013. We investigated the dynamic changes of antibody response to this virus over 1 year postinfection in 25 patients in Suzhou City, Jiangsu Province, China, who had laboratory-confirmed infections during the fifth epidemic wave, October 1, 2016-February 14, 2017. Most survivors had relatively robust antibody responses that decreased but remained detectable at 1 year. Antibody response was variable; several survivors had low or undetectable antibody titers. Hemagglutination inhibition titer was >1:40 for <40% of the survivors. Measured in vitro in infected mice, hemagglutination inhibition titer predicted serum protective ability. Our findings provide a helpful serologic guideline for identifying subclinical infections and for developing effective vaccines and therapeutics to counter H7N9 virus infections.

Incidence and epidemiology of intussusception among children under 2 years of age in Chenzhou and Kaifeng, China, 2009-2013.

INTRODUCTION: In China, rotavirus is the leading cause of diarrhea hospitalizations among children aged <5 years. A locally manufactured rotavirus vaccine is available for private market use, but little is known about its coverage. Given the impending availability of newer rotavirus vaccines, we evaluated intussusception rates among children aged <2 years to better understand intussusception epidemiology for future vaccine safety monitoring. METHODS: We conducted a retrospective review at 4 hospitals in Chenzhou City of Hunan Province and Kaifeng City of Henan Province. We identified intussusception cases admitted during 2009-2013 by reviewing medical records with the ICD-10 discharge code for intussusception and extracting demographic and clinical information from the electronic clinical record systems. RESULTS: During 2009-2013, 1715 intussusception hospitalizations among 1,487,215 children aged <2 years occurred in both cities. The average annual intussusception hospitalization incidence was 112.9 per 100,000 children aged <2 years (181.8 per 100,000 children <1 year; 56 per 100,000 children 1 to <2 years). Intussusception incidence was low among infants aged <3 months and peaked at age 6-8 months. No clear seasonality was observed. Ultrasound was used to diagnose 95.9% of cases. Enema reduction was performed in 80% cases; 25% of cases in Chenzhou and 16% in Kaifeng required surgical intervention. No deaths were reported. The median time between symptom onset and admission was 1 day. CONCLUSIONS: This study provides information on intussusception incidence and epidemiology in two cities of China during 2009-2013. Monitoring intussusception rates in this population will be important in the post-rotavirus vaccine era.

[Epidemiology of intussusception related hospitalizations in children aged <2 years in Suzhou, 2007-2013].

OBJECTIVE: To understand the epidemiological and clinical characteristics of <2 years old children hospitalized due to intussusceptions. METHODS: Clinical and demographic data of <2 years old children hospitalized due to intussusception between January 2007 and August 2013 were retrospectively collected in Affiliated Children' s Hospital of Soochow University in Suzhou. The incidence data, age distribution, seasonality and clinical characteristics of hospitalized intussusceptions cases were analyzed. RESULTS: A total of 594 intussusception-related hospitalizations were identified during this period in children aged <2 years, no death occurred. The crude incidence of hospitalized intussusception was 57.3 per 100,000 in children aged <2 years (95%CI: 52.8-62.1), and 100.6 per 100,000 in children aged <1 year (95%CI: 92.1-109.8). The male to female ratio was 1.90:1. Up to 85.4% (507/594) of the cases were aged <1 year, and 66.2% (393/594) of the cases were aged 3-8 months. The incidence peaked in age group 5-8 months. The median age of the cases was 6.8 months (QR=4.4), and increased from 6.3 months (QR=4.2) in 2007 to 7.3 months (QR=4.0) in 2013. No obvious seasonality was observed. Main symptoms or signs included vomiting (83.2%, 494/594), abdominal mass (81.1%, 482/594), and bloody stool (64.5%, 383/594). Abdominal ultrasonic testing was the most frequently used diagnostic approach (98.7%, 586/594). Up to 86.2% (512/594) of patients were successfully treated by surgical intervention. The main sites for acute intussusception in children aged <2 years were ileocolic (34.5%, 183/530), ileo-ileo (30.8%, 163/530) or ileo-ileo-colic (27.9%, 148/530). CONCLUSION: The incidence of hospitalized intussusception in children aged <2 years was high in Suzhou. It is necessary to establish an active surveillance system to provide baseline data for the evaluation of rotavirus vaccine safety.